Usually, in rolling bar steel, round bars and flat bars are rolled in a manner different from that for angles and channels, due to the difference between their cross-sectional configurations, so that it is very difficult to roll the two types on the same rolling line. More specifically, the former type is ideally finished into products by alternately arranging horizontal rolling mills and vertical rolling mills on the rolling line and alternately applying pressure in the directions of thickness and width. For the latter type, however, a pressure must be successively increased while being gradually applied in a same direction, so that only horizontal rolls are provided on the rolling line, whereby products are finished by successively repeating pressure in the direction of thickness.
In consideration of these circumstances, "convertible type rolling mills" in which stands are capable of horizontal-vertical shifts have recently been put into practical use. In these convertible type rolling mills, stands are rearranged depending on the type of raw material to be rolled to be fed along a line, and various bar steels, such as round bars, flat bars, angles, channels, etc., can be rolled on the same rolling line.
FIGS. 8 and 9 show an example of a convertible type rolling mill. When a roll of the rolling mill 1 is in a vertical position, guide stand 4 is in an upright position, as shown in FIG. 8, and the rotational force of motor 6 is transmitted to the rolls of rolling mill 1 successively, through universal joint 5, speed reducer 3, and universal joint 2. In shifting the roll of rolling mill 1 to a horizontal position, on the other hand, speed reducer 3 and universal joint 2, along with guide stand 4, are rearranged as shown in FIG. 9.
FIGS. 10 and 11 show another convertible type rolling mill. In making a shift from the horizontal position shown in FIG. 10 to the vertical position shown in FIG. 11, rollers 7 and speed reducer 10 are separated at the location of universal joint 9, rollers 7 are mounted in the vertical position in guide stand 8 which contains a speed-reduction distributing gear therein, and universal joint 9 is coupled to guide stand 8. The force of rotation of motor 11 around a horizontal axis is transmitted, as a force of rotation around a vertical axis, to a roll of rollers 7 by means of the speed-reduction distributing gear of guide stand 8.
Further, FIG. 12 shows a convertible type rolling mill of another type, in which vertical type rolling mill (inner stand) 12 is incorporated in guide stand 19. In this type, the rotatory force of motor 17 is transmitted to a pair of universal spindles 13 through speed reducer 16 and gear boxes 14 and 15. In making a shift from vertical to horizontal, vertical inner stand 12 is removed, and a horizontal inner stand (not shown) is incorporated in guide stand 19. The horizontal inner stand and speed reducer 16 are coupled by means of another pair of universal spindles 18 having a horizontal axis.
In the first, second, and third convertible type rolling mills described above, however, the guide stand to receive the inner stand has a complicated mechanism, so that its maintenance requires much labor, and the machine itself is expensive. In the rolling mills of these types, therefore, partial reconstruction utilizing existing line equipment is hardly possible, so that new equipment must be installed after removing all the existing equipment. Thus, the equipment cost is enormous, and uneconomical. In the first and second rolling mills, moreover, the stand rearrangement requires a lot of time, thus retarding the whole operation and lowering productivity.
The present invention has been contrived in consideration of these circumstances, and its object is to provide a rolling mill with interchangeable roller apparatus in which the rearrangement of stands can be achieved by a minor reconstruction of existing equipment, and horizontal-vertical shifts can be effected in a short period of time.